Glass bending moulds



R. E. RICHARDSON 56,734 GLASS BENDING MOULDS Oct. 21, 195

4 Sheets-Sheet 1 Filed June 18, 1956 INVENTOR. RONALD E RICH/7R 05o 4%,;n W r Arromwsys Oct. 21, 1958 Filed June 18, 1956 4 Sheets-Sheet 2uvs/wax: Row/up E. Ric :MRoSmv R. E. RICHARDSON GLASS BENDING MOULDSOct. 21, 1958 4 Sheets-Sheet 3 Filed June 18, 1956 1958 R. E. RICHARDSONGLASS BENDING MOULDS 4 Sheets-Sheet 4 Filed June 18, 1956 BOA ALB E.RIC/M $050M 5y /%v% A mnsys 2,856,734 Patented Oct. 21, 1958 GLASSBENDING MOULDS Ronald E. Richardson, Oshawa, Ontario, Canada, assignorto Pittsburgh Plate Glass Company, Pittsburgh, Pa.

Application June 18, 1956, Serial No. 592,111 Claims priority,application Canada July 2, 1955 3 Claims. (Cl. 49-437) This inventionrelates to improvements in the construction of moulds such as areemployed in the bending of elongated glass sheets to curved form. Theadvent of wrap-around Windshields in automobile design has given rise tothe need for eflicient moulds for the initial processing of theelongated glass sheets that will ultimately form the laminated safetyglass of such wrap-around windshield. A wrap-around" windshield consistsof an elongated sheet of laminated glass of gentle curvature at itscentre, the radius of curvature decreasing sharply at each end until theglass is extending almost perpendicular to the main body of the glass.

The technique employed in forming such wraparound Windshields, or likeobjects of curved laminated glass for automobile rear windows or otherapplications, is to lay a pair of flat elongated glass sheets on a mouldwhich is so arranged as to tend to take up its final configuration whenso permitted by the softening of the glass. The mould and glass sheetsare passed through a furnace in which the glass is raised to atemperature sufiicient to render it yieldable to the forces exerted uponit by the mould. In this manner the required shape is imparted to theglass. Subsequently the two sheets are annealed, an intermediatelamination of a synthetic resinous material is placed between them andthey pass to the rolling and pressure treatments before emerging as afinished product. A similar bending operation is employed inmanufacturing the tempered type of non-laminated safety glass.

The present invention is concerned with the construction of moulds forthe preliminary bending of one or more such sheets during passagethrough a furnace.

It has become the practice to form moulds for this purpose with pivotedend portions each of which either can be swung into a first position(when the fiat, cold glass is originally placed in position thereon)subsequently referred to as the flat position of the mould, or canmoveinto a second position (the curved.position of the mould) as theresistance to bending of the glass decreases on exposure to highertemperatures. Weights tending to urge the movable portions of the moldinto such latter positions are normally provided.

Dificulty has been experienced in the past in obtaining smooth movementof such end portions of the mould, such as to ensure regular andcontrolled bending of the glass. There has been a tendency for themovable end portions of the mould first to bind in one position and thento move jerkily as the glass softens, producing highly disadvantageouseffects on the smoothness of curvature of the finished glass. It isbelieved that these difliculties are due to excessive friction in thehinge devices that have in the past been employed in glass bendingmoulds of this character.

It is the object of the present invention to provide hinge means in sucha glass bending mould, in which the friction between the two partsconnected by the hinge means is maintained both as small as possible andas uniform as possible.

To this end, the invention in its broad aspect consists of consists of apair of side bars 5,

a glass bending mould having a main mould portion and at least onesubsidiary mould portion pivotally connected to said main mould portion,wherein such pivotal connection comprises a knife edge secured to one ofsaid portions and co-operating with a groove formed on the other of saidportions. Preferably, a pair of knife blades each with a co-operatinggroove is employed, one disposed on each side of the mould.

Glass bending moulds normally fall into one of two classesconcave mouldsor convex moulds-depending on whether the glass is cradled within aconcavely curved mould or wrapped around a convexly curved one. Thepresent invention is equally applicable to use with either class ofmould. It will, however, only be exemplified below with reference to aconcave mould, its use with a convex mould being analogous.

In a more specific form the invention may thus be defined as a glassbending mould of the concave type having a main mould portion in theform of a pair of spaced generally parallel bars, and at least onegenerally V- shaped end mould portion pivotally connected to one end ofsaid main mould portion so that the bars of said end mould portion areeach contiguous with the end of one of said bars of the main portion inthe concave position of the mould, wherein such pivotal connectioncomprises a pair of knife edges secured to said main mould portion andeach situated at the end of one of the bars thereof and positioned toform extensions of one another and thus form a line of pivoting, and apair of members secured to the end of each bar of said end mouldportion, said members being formed with grooves positioned to cooperatewith said knife edges.

One half of a concave skeleton type mould embodying the invention isillustrated by way of example in the accompanying drawings. The otherhalf of the mould is identical in mirror image, and has thus not beenillustrated.

Figure 1 shows a initial flat the glass;

Figure 2 is a side view of the part of the mould half seen in Figure 1,with the parts in the same position;

Figure 3 is a view similar to Figure 2 but with the parts in the curved(in this type of mould concave) position assumed after bending of theglass;

Figure 4 is an enlarged side view of a fragment of this mold taken onthe line IV-IV in Figure 5; and

Figure 5 is an end view of the fragment seen in Fig ure 4.

The main side bars of the mould are each designated by the referencenumeral 1, the movable end portion at the end of the mould visible inthe drawings, being shown generally at 2. This movable end portion 2 isitself composed of two relatively movable mould sections 3 and 4. Thedetailed structure of the end portion 2 of the mould and the nature ofthe relative movement between the sections 3 and 4 form the subjectmatter of copending United States patent application Serial No. 591,913and will not be elaborated upon further in this specification. Sufficeto say that the mould section 3 each of which is arranged, in theconcave position of the mould (Figure 3), to

plan view of the mould half in the position of the parts prior tobending of .form a contiguous smooth continuation of a main side bar 1.The end of each side bar 5 adjacent the end of a main side bar l issecured by suitable struts 5a to an arched bracket 6 to which there isfurther secured an arm 7 extending generally away from the end portion 2and, when the parts are in the flat position of Fig ures 1 and 2,upwardly at an angle approximately equal to that through which it isdesired to pivot the end portion 2 of the mould. As will appear fromFigures 1, 4 and 5, which latter are enlarged side and end views of abracket 6 and its associated parts, reinforcing side plates 8 aresecured to each side surface of such bracket. A vertically disposedupstanding plate 9 is secured to .the...end of.eacl1- main sidezbar 1toextend perpendicu- .-...tlarly.outwardlyztherefrorni ail he .uppenedge of. each: plate l.9 is rounded. ofi" .to-semi-circula-rcrossrsection. and serves to definethe axisaboutwhich. theendportionZ ofthe ...:mould.rotatesw-The innerapices o-f'the bracketswi and,...reinforcing plates .8 are. madersimilarly, arcuate to. form acomplementaryv surfacethat .will be readily able to slide smoothly overthe upper edges of the platesfi on piv- .otalrnovement oftheiendportion2 of the mould between ..,.the.-positions seen inflFigures 2.and 3. Eachplate. 9 ter- Mminates at its. outward :end in an upwardly-projecting,finger. 9a; .-.The twodingers 9a.accurately-determine the transversealignment of. theend portionxZ in relation to .themain portion ofthetmoul-d and thus ensure registrationvof thesidebarsl and 5.

Weights 141 are secured-to. the extreme :ends of the two .:arms 7,thesearins-beingdisposed outwardly ofethe side bars 1 ofthe mould,asbest-seen fromjigure 1, in order to be free to movedownwardlywithoutencountering the Normally,

The weight and rigidity or the tion 2 of the mould, the tip 26 of whichend portion presses upwardly against the underside of the glass 11 atits extreme end. The parts will remain in the positionseen inFigure 2against the force exerted by the weights 10, until the glass begins tosoften as a result of increasing temperatures that it encounters onbeing fed on a continuously moving belt through an oven.

Gradually the upward bending force exerted by the weights ltlwill takecharge and the glass will allow each 1 of the end portions 2 to swingslowly and uniformly upward, until the two arms 7 each come to reston-one of a pair of adjustable stops 12 mounted each on the outside ofone ofthe side bars 1 of the rnould."-The parts will then be in. theposition illustrated in Figure 3 ...land:the glass. 11 will be smoothlybent to the required shape. It will benoted that the main body of theglass :gsagstsufiiciently to bring its edges into contact with the fulllength of the side bars 1. The degree and area of -;appl-ication of'heat, combined with the comparatively narrow transverse dimension of themould, normally permit no significant transverse sagging, althoughtransverse sagging can be provided for if desired.

Theuse in a glass bending mould, of the type of piv- "otal connnectionconsisting of rounded knife edge with a complementary co-operatinggroove, is found to provide a very smoothly operating mould withconsequent improvements in the quality of glass produced thereby. lti'smoteSsentiaI for the knife edge to be'forrned on apart of. the fixedmain portion of the mould. .it may be-secured to the movable endportion, while the main portion carries the co-operating groove.

If desired Moreover, the degree of rounding of the knife edge may bevaried as:necessary. It may be reduced so as to produce virzwtually asharp knife blade edge, but some degree of curva- 4 ture will normallybe desirable having regard to the class of steel from which the mouldwill be made and the comparatively rude treatmentrthat the mould willexperience 111 use.

The drawings also illustratea further device known as a teeter which mayconveniently be incorporated in the same mould as the knife edgebearings. This teeter device. which is shown generally at 13 is thesubject of co- .pendin'g'...United. States patent application Serial No.

Gther parts of the mould visible in the drawings are a thermal ballastdevice 14 the function of which is described in the former of saidco-pending applications concerned with the construction and operation ofthe end portion 2; supporting members 15 for such thermal ballast device14; conventional bracing members 16 extending v.between the side bars llandbetween parts of the end portion.2 such as side bars 5; conventionalsupporting legs 41; .and other parts not germane to the presentinventionand described indetail in one of said co-pending applications Certain of.thebracingmembers 16 that connect the parts of. the sections 3 and 4 ofthe end por- .tion 2 project somewhat downwardly from these sections inorder .to reduce themass of metalclosely adjacent-the glass. sheet/and.thus.;minimize r local .cooling. efiects thereon.

.Lclaim:

1. A glass bending mould having a. main. mould por- .tion'and atleastone subsidiary mould portion pivotally connected to. saidxmain:mould. portion wherein such pivotal!connectionzlcomprises aknife edgesecured to one '2 ofrsaidportions and co-aoperating with a. grooveformed on theirother olisaid portions.

2..A glassnbending. mould having a main mould portion and atleast one.subsidiaryrnould portion pivotally connected to saidmain mould portion,wherein such pivotal connection comprises a pair of knife edges securedto 1 said main mould ;portion' co-operating with a pair of groovesformed in avmembersecured to said subsidiary .mould portion.

3. A..glass bending mould ofv the concave type having a maimmouldportion in the form of a pair of-spa'ced :generally. :.parallel bars;and atleast one generally V- shaped.end'mouldportion pivotally connectedto one *end ofzsaid mainimould portion so that the bars of said endmouldiportionare.each contiguous'with the end of one of said barsofrthema'in'portion in the concave position of the mould,;wherein suchpivotal connection comprises zap-air. .ofi'knifeiedges secured to saidmain mould portion .Handseachi'situated atthe end ofone of the barsthereof andxpositioned toform'extensions of one another-"and *thus forma line of pivoting, and a pair of members secured to the end of each/barofsaid end mould portion, -.saidmemberstbeing'formed with groovespositioned to co-operate with said knife edges.

References Cited in thefile of this patent 'UNIT'ED STATES PATENTS"760,959 Connington May 24,1904 2,021,061 Hedman Nov. 12, 1935 2,121,481I Flum'erfelt June 21, 1938 2,348,279 'Boyles et a1. May 9, 19442,688,210 Gendrisak Sept. 7,1954

. FOREIGN PATENTS 1,089,973 France Oct. 3, 1954

